This invention relates to video signal processing, and, more particularly, to deinterlacing a video signal.
Personal computers, along with their monitors, are used in nearly every field of work. Many fields also make use of microprocessors for encoding and decoding video signals. For example, in the medical field, a surgeon working at a large university medical center consults on a surgical procedure taking place in a remote clinic. The surgical procedure being performed in the remote clinic is captured using a video camera and transmitted to a personal computer in the university medical center for real time display and viewing by the surgeon.
A problem that occurs in the scenario described above is that the displayed video often contains defects known as artifacts. Some artifacts occur as a result of a mismatch between the rate at which information is acquired during the interlaced encoding process and the rate at which it is displayed on a progressive monitor, such as a personal computer monitor, during the decoding and display process.
An interlaced video frame contains two fields. The first field consists of the odd lines in the interlaced video frame and the second field consists of the even lines in the interlaced video frame. When displayed on an interlaced video system, the lines of the two fields are displayed in an alternating fashion. All odd lines of the interlaced video frame are displayed, and one-sixtieth of a second later, all even lines of the interlaced video frame are displayed.
In a system that displays an interlaced video signal on a progressive monitor, the two fields of the frame are combined and displayed at a rate of one-thirtieth of a second per frame. Combining the two fields captured every one-sixtieth of a second and then displaying the combined fields at a rate of one thirtieth of a second results in combing artifacts in areas of the displayed video that contain motion. These artifacts blur the edges of moving objects, which in the example described above can create a significant problem for the consulting physician in that critical areas of the displayed video can appear blurred.
One solution to this problem is to use motion compensated interpolation during the encoding and decoding of the video signal to reduce the blurring introduced by the combing artifacts. Motion compensated interpolation creates a missing block in a video frame by averaging over the immediately previous and following blocks that are available to the decoder. Unfortunately, this solution is computationally complex and requires a large amount of memory and a powerful processor to implement.
For these and other reasons there is a need for the present invention.
A system for deinterlacing a video signal is described. In one embodiment of the present invention, a detector identifies regions in a video signal that contain inter-field motion. An interpolator is coupled to the motion detector and is capable of generating an interpolated value, when the motion is detected.